What should I do in this situation?

Why might you never see him again? Is he going somewhere?

Well his not going somewhere, we both have been in this show and the show is comeing to an end. I know we could meet up, but I feel like that might not happen.

How about letting him know that you enjoy his company and would like to continue the friendship once the show wraps up? That way, you aren’t jeopardizing the relationship and are sparing your pride (or a broken heart). And if he does finally break up with her, you might have a better shot.

Personally, if someone I was interested in regularly talked negatively about their SO, it would bring any desire to have a relationship with the person to a screeching halt. And particularly if there was any flirting involved. If he does it now, his behavior is unlikely to change should he start dating you.

completely agree with @Pied_Pfeffer

He doesn’t flirt with me, never comes close. I wouldn’t like a man whom doesnt treat his girlfriend correctly and he only tells me these things about her when i find him upset and ask whats wrong.
I like him because he is kind and careing. My problem is I like him so much and i can see he’s unhappy. And i realize that not my place to say that. It’s just that he is not the type that ever gives up. And he keeps on trying and trying again. THAT is what i love about him. And my problem is that he’s girlfriend isn’t trying.

Well you sound like a nice girl to me, and it sounds like your moral compass is pointing in the right direction.
I think all you can do is continue to be his friend, offer your support, and be there, in the event of something changing.

When you are in a show with someone, feelings are more intense than they are in real life. This is the nature of actors and being thrust into make-believe.

If he doesn’t flirt with you, and has a girlfriend, he’s not interested in you outside the show. Give him an avenue to connect with you, like friending him on facebook, and return to your regular life.